These studies are designed to: (1) evaluate the influence of in utero exposure to environmental toxicants (for example, Diethylstilbestrol) on fine structure of the male and female reproductive tracts; (2) study the influence of environmental chemicals on cell differentiation and cell surface ultrastructural features; (3) develop and utilize models which will determine the cell surface features associated with preneoplastic and neoplastic transformation by scanning and transmission electron microscopy and correlative histology; and (4) employ histochemistry to identify and localize morphological markers to assess the cellular or subcellular responsiveness to foreign agents.